From your description it might seem that you have a "Rolex Ultra Prima", model number 74108, which was introduced by Rolex December 9th, 1930*. The number stamped on it could be a serial number but those serial numbers are from the early 80's**. It is very hard to tell since there are no pictures. I suggest you go to your local Rolex dealer who will have more knowledge and will be able to use a loupe and inspect the watch in person. In conclusion, from the information you gave it seems fake.*source: The Best of Time:Rolex Wristwatches an Unauthorized History by James M Dowling & Jeffer P. Hess. **source: www.timeandgems.com
